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  • Küçük Resim
    Öğe
    Bazı protein ve enzim çözeltilerinde NMR rölaksasyon zamanlarını modüle eden ilgi zamanlarının T1/T2 oranı kullanımı yoluyla belirlenmesi
    (2016) Zengin, Bilgin; Yılmaz, Ali
    Bu çalışmada, Hemoglobin ve üç enzim (Pepsin, Proteaz ve ? -chymotrypsin) çözeltisinin H2O’ daki 1/T1 (spin-örgü) ve 1/T2 (spin-spin) rölaksasyon oranları 64 MHz (1.5 Tesla) MR pektrometresi kullanılarak oda sıcaklığında konsantrasyona karşı incelendi. Hemoglobinin D2O ve H2O/D2O (0.1ml H2O+0.9ml D2O) çözeltilerindeki rölaksasyon oranları ayrıca 400 MHz (9.4 Tesla) NMR spektrometresiyle konsantrasyona ve sıcaklığa karşı incelendi. 64 MHz’ deki 1/T1 ve 1/T2 rölaksasyon oranları, Hemoglobin ve enzim konsantrasyonuyla lineer olarak artmaktadır. 400 MHz’ de belirlenen 1/T1 ve 1/T2 de Hemoglobin konsantrasyonuyla lineer olarak artmaktadır. 400 MHz’ de Hemoglobin çözeltisinin sıcaklık bağlılığı, 1/T1 ve 1/T2 rölaksasyon oranlarının sıcaklık artışıyla lineer olarak arttığını gösterdi. Rölaksasyon mekanizmasını modüle eden ilgi zamanı (? ) bu tezde türetilen teori kullanılarak, yüksek manyetik alan (9.4 Tesla) ve düşük manyetik alan (1.5 Tesla) için hesaplandı. 64 MHz’ deki ? değerleri; Hemoglobin için 2.0017ns, Pepsin için 5.3225ns, Proteaz için 2.2865ns ve ? -chymotrypsin için 3.8398ns olmaktadır. Buna ilaveten, Hemoglobinin D2O ve H2O/D2O çözeltileri için 400 MHz’ deki ? değerleri sırasıyla 1.22ns ve 1.27ns olmaktadır. Tezde elde edilen veriler; protein ve enzimler küresel simetrik kabul edildiği zaman, T1/T2 rölaksasyon oranlarının ? değerlerinin doğru hesabı için kullanılabileceğini gösterdi. Protein ve enzimler için elde edilen sonuçlar; rölaksasyon oranlarına moleküler takla tarafından modüle edilen dipolar etkileşmenin neden olduğunu önermektedir. Serbest ve bağlı su arasındaki protonların hızlı kimyasal değiş tokuşu da sürece katılmaktadır. Anahtar Kelimeler: 1/T1 spin-örgü rölaksasyon oranı, 1/T2 spin-spin rölaksasyon oranı, 64 MHz MR, 400 MHz NMR, ? ilgi zamanı, dipolar etkileşme, hemoglobin, pepsin, proteaz, ? -chymotrypsin
  • [ X ]
    Öğe
    Elimination of Radiation Damping Effects from the NMR Relaxation Curves of H2O/D2O Mixtures Containing Protein and Ions
    (Physical Soc Republic China, 2013) Zengin, Bilgin; Koylu, Mehmet Zafer; Korunur, Sibel; Yilmaz, Ali
    In this work the T-1 and T-2 curves of H2O/D2O mixtures were obtained for several fractions of H2O and also for different amounts of albumin and manganese. The experiments were carried out with a 400 MHz proton NMR spectrometer. The T-1 and the T-2 curves were determined by the inversion recovery (IR) and Carr-Purcell-Meiboom-Gill (CPMG) sequences, respectively. The relaxation times in residual water and in a mixture with 0.05 ml H2O were found to be reliable either in the presence or in the absence of albumin. The mixtures containing 0.1 ml or higher H2O suffer from radiation damping (RD). RD was removed gradually by addition of albumin or manganese. RD in the protein solution with 0.1 ml H2O was removed by adding 1 mu g of manganese to one ml of solution. The data suggest that the relaxation times in H2O/D2O mixtures are measurable by conventional methods upon the addition of appropriate amounts of manganese and albumin.
  • [ X ]
    Öğe
    The Examination of a Variety of Different Ions Added to the Crown Ether Derivatives with High Field NMR Spectrometer
    (Maik Nauka/Interperiodica/Springer, 2017) Askin, Muzaffer; Zengin, Bilgin; Korunur, Sibel; Kor, Harun; Koylu, M. Zafer
    The current study involves the measurements of T-1 relaxation time of complexes three different crown ethers (4-aminobenzo-15-Crown-5, 1-Aza-18-Crown-6, 1-Aza-15-Crown-5) and two different ions sodium perchlorate (NaClO4), lithium perchlorate (LiClO4) by a 400 MHz NMR spectrometer. The association constants (K-a) of the complexes were determined on the basis of the evaluation of these measurements using the Benesi-Hildebrand method that we have modified. These association constants were consistent with those obtained from H-1 NMR titration technique. As a result, it can be speculated that binding constants could be measured using T-1 relaxation time when chemical shifts are very small or cannot be observed.
  • [ X ]
    Öğe
    Observation of Triplet Traces Obtained with Inversion Recovery Method in Both Residual Water- and H2O/D2O-Albumin Mixture by Using 400 MHz Proton NMR
    (Asian Journal Of Chemistry, 2013) Yilmaz, Ali; Zengin, Bilgin; Korunur, Sibel
    NMR studies involving H2O/D2O mixtures are mainly based on a single spectrum of water. However, some recent papers have revealed the presence of an HDO triplet in H2O/D2O, which is caused by the splittings of H2O signal by deuterium (D). Observation of inversion recovery (IR) traces of this triplet should be very useful for analyzing relaxation data in such mixtures. In this work, in order to obtain the traces, inversion recovery signal intensities of residual water and a mixture of 0.10 H2O and 0.90 D2O were acquired versus a set of short delay times in the presence or absense of 0.2 g albumin. T-1 and T-2 curves of the same samples were also obtained by using different sets of much longer times for checking the effect of radiation damping on the traces. Experiments were carried out with a 400 MHz proton NMR spectrometer equipped with a topspin programme for relaxation measurements. Inversion recovery data of the traces and T-1 curves were obtained with the inversion recovery method, while T-2 curves were obtained with the Carr-Purcell-Meiboom-Gill method. Data was processed through an analysis programme of the topspin. Data showed that radiation damping is effectively reduced upon addition of albumin. Furthermore, the data of the residual water- and the mixture with albumin demonstrated the traces of the triplet at the initial part of a single inversion recovery line. Our results suggest that the splitting of water proton signal by deuterium can be detectable by the inversion recovery method for D2O- and the mixture containing albumin.